This invention relates to a vehicle air bag assembly, and more particularly to an air bag cushion including a flow barrier element of substantially inverted T-shaped geometry disposed at the interior of the air bag for the dispersal of inflation gas into connected portions of the cushion for protection of the thorax and head of a vehicle occupant during a side collision event.
It is well known in motor vehicles to provide an air bag assembly for the protection of a vehicle occupant. Such air bag assemblies typically include an inflatable cushion structure in fluid communication with a gas emitting inflator. Upon the occurrence of predetermined vehicle conditions, such as deceleration exceeding a certain level, a signal is sent via appropriate sensors to the gas emitting inflator thereby causing the inflator to discharge gas into the air bag cushion forcing the air bag cushion outwardly from a stored position into an operative position between the occupant to be protected and the interior portions of the vehicle. The presence of the inflated air bag cushion between the occupant and the interior portions of the vehicle provides a cushioning effect as the occupant impacts the inflated cushion thereby dissipating the kinetic energy of the occupant in a substantially controlled manner.
It is also known to provide an air bag assembly placed and configured for side impact protection of a vehicle occupant. The prior art has disclosed side impact air bag assemblies which have either one cushion or a plurality of cushions which deploy to protect the head and thorax portions of the vehicle occupant. In such side impact air bag assemblies, it may be desirable to promote early inflation of the thorax protection portion of the cushion rather than having inflation gas directed initially and preferentially to the head protection portion during the early stages of activation. At the same time, it may be desirable to deploy the head protection portion of the cushion to a substantially vertical orientation adjacent the occupant to be protected. Yet further, it may be desirable to inflate the side air bag cushion utilizing a relatively small volume of inflation gas without using excessive inflation gas to inflate regions of the air bag cushion unnecessarily.
It is known to utilize expansion limiting tether elements in the form of elongate straps across inflatable air bag structures to yield predetermined and desirable inflated geometries. However, the use of traditional tethering elements such as elongate straps and the like may substantially increase the complexity of the manufacturing process while adding mass and bulk to the finished product.
The present invention offers advantages and alternatives over the prior art by providing a side impact air bag cushion which incorporates an integral zero-length tether element which promotes desirable early inflation of the thorax protection portion of the cushion as well as the substantially vertical inflated orientation of the head protection portion while simultaneously reducing the total inflated volume of the cushion. Accordingly, the present invention is believed to provide a new and useful advancement over the prior art.
These advantages are accomplished in a potentially preferred form of the present invention by providing an air bag assembly in a vehicle having an inflator for generating inflation gas and an air bag cushion deployable upon generation of gas by the inflator. The air bag cushion includes an upper boundary and lateral sides extending away from the upper boundary. The air bag cushion includes a lower inflatable portion for cushioning the thorax of the vehicle occupant. The air bag cushion further includes a substantially contiguous upper inflatable portion distal from the inflator for cushioning the head of the vehicle occupant. A flow blocking element in the form of a zero-length tether having a substantially inverted T-shaped configuration is disposed at the interior of the air bag cushion adjoining opposing interior surfaces of the air bag cushion so as to restrict gas flow between portions of the cushion at the location of the zero-length tether. The base portion of the zero-length tether is oriented in substantially transverse relation to the lateral sides at a latitude along the air bag cushion between the upper and lower inflatable portions so as to establish a boundary between the head protection portion and the thorax protection portion of the cushion. The substantially vertical leg portion of the zero-length tether extends away from the base and into the head protection portion of the cushion thereby stabilizing the head protection portion upon inflation. Advantageously, the air bag cushion of the present invention may be constructed utilizing cost effective and highly efficient seaming or other surface connecting procedures without relying on separate tethering elements.
According to one aspect of the present invention, the air bag cushion may be formed from a single piece of material by folding such a piece of material upon itself along a predetermined fold line to form a folded structure of two layers and applying at least one perimeter seam around the perimeter of the folded structure to define a gas receiving enclosure. A flow barrier element in the form of a zero-length tether is applied at an interior position within the perimeter boundaries of the folded structure so as to join the two layers together at the location of the zero-length tether. The geometry of the flow barrier element is substantially in the form of an inverted T-shaped geometry including a substantially horizontal base and a substantially vertical leg projecting upwardly away from the base portion. The substantially horizontal base is preferably disposed at a latitude substantially corresponding to the boundary between the portion of the air bag cushion deployable adjacent to the thorax of an occupant to be protected and the portion of the air bag cushion deployable adjacent to the head of the occupant to be protected. The zero-length tether making up the flow barrier element may be introduced by sewing together the opposing surfaces of the air bag cushion as well as by other means including welding or adhesively bonding together the layers of the folded structure. The zero-length tether may be applied at the time that the connective perimeter seams are applied and may be of structurally similar character to such connective perimeter seams thereby simplifying the construction process. The base and leg portions of the flow barrier element may be interconnected or separate from one another.
The structure of the air bag cushion according to the present invention is such that inflation gas entering the air bag cushion is channeled around the base of the flow barrier element before entering the head protection portion of the air bag cushion. The base of the flow barrier element restricts the flow path from the thorax protection portion and into the head protection portion thereby promoting early preferential expansion of the thorax protection portion of the air bag cushion. Upon inflation of the head protection portion, the vertical leg of the flow barrier element separates the head portion of the cushion into vertical sections and promotes the stable vertical orientation of the head protection portion relative to the head of the occupant to be protected.